SL28 is a Kenyan cultivar — bred at Scott Laboratories in Nairobi, shaped by East African terroir, and considered one of the highest cup-quality varieties in the world. Planting it in Costa Rica's West Valley is the kind of deliberate variety experiment that the micro-mill era made possible, and the "Kenia" name signals exactly that lineage.
Washed processing strips the equation down to its essentials: variety plus altitude. At 1,600m in Grecia, the bean sits in Costa Rica's quality altitude band, and washed fermentation removes the fruit variables that [honey or natural processing](/blog/coffee-processing-methods-explained) would introduce. What you're tasting is primarily what SL28 and this terroir put into the seed.
The black currant character is the first thing to explain. SL28 was originally selected in part for its intense, almost Kenyan-style fruit profile — this comes from its Bourbon lineage ancestry combined with the variety's specific genetic expression of citric and malic acids. Citric acid is the only organic acid in coffee that consistently exceeds its sensory detection threshold; at light roast, with chlorogenic acid levels still high and minimal quinic acid formation, the brightness is sharp and distinct rather than diffuse. The grapefruit note sits on the same citric axis. Malic acid adds the plum and dark fruit character underneath, and brown sugar comes from Maillard reaction products — the nutty, caramelly compounds built at light roast before the process tips into heavier dry distillates.
SL28 produces large beans and low yield — it's a high-investment variety. The washed process keeps the cup clean enough that the variety's character reads clearly rather than getting buried under processing artifacts.
Chemex scores 96/100 — tied for top rank with a significant gap to other methods — because the thick bonded filter's exceptional clarity directly serves SL28's complex acid expression. Black currant in SL28 is an interplay of bright, deep, and sparkling acidity; any oils or fines in the cup muddy that acid resolution. Chemex removes everything. At 510μm the grind is 40μm finer than default for light roast density, and 94°C water holds full extraction temperature with no further adjustment needed for processing or variety. The slow drawdown extends contact time naturally, which matters for SL28's large beans — more time in contact means the slower-extracting compounds responsible for the plum and brown sugar notes have sufficient time to dissolve into the filter bed before drawdown completes.
Troubleshooting
sour: Grind finer by ~22μm and raise temp to 95°C. Chemex's thick filter already slows drawdown, but SL28's large dense beans can still undershoot if grind is coarse for the roast level. Sour output means extraction stopped at the citric acid phase — the blackcurrant and plum complexity never developed. Finer grind corrects contact time.
thin: Increase dose to 29g or reduce water to 419g. Chemex strips all oils from this washed SL28, leaving body entirely dependent on TDS. At the wide ratio end, the grapefruit and brown sugar notes both collapse into the background. More coffee mass is the most reliable fix before reaching for a metal filter.
Don Joel Kenia on the V60 runs at 460μm and 94°C — the 40μm finer grind compensates entirely for light roast's reduced solubility, with no further adjustment needed for SL28 or washed process since both have neutral extraction profiles at this setting. At these parameters, the V60's fast, technique-dependent flow means the critical variable is pour control: SL28's high-density large beans at 460μm can channel easily if the bloom doesn't fully pre-wet the grounds. The cone geometry keeps fines concentrated at the center where heat retention is highest, which actually helps SL28 — the high-quality variety benefits from even temperature throughout extraction because its complex acidity requires consistent thermal energy to fully dissolve the darker fruit compounds (plum, black currant) alongside the brighter grapefruit. At 1:15-1:16, the ratio builds enough concentration for the SL28 blackcurrant and grapefruit to register as distinct layers.
Troubleshooting
sour: Grind finer by ~22μm and raise temp to 95°C. SL28's large beans and dense structure can undershoot at 460μm — sour output means extraction stopped at the fast-extracting citric and phosphoric acid phases before the malic plum and Maillard brown sugar developed. Finer grind increases surface area through the dense cell walls.
thin: Add 1g to dose (20g) or reduce water by 15g. Washed light roast SL28 has high solubility potential, but the V60's paper filter strips oils and the 1:15-1:16 ratio can run thin if pour timing lets the bed dry too fast. More coffee keeps TDS up — metal filter option adds body without dose change.
The Kalita Wave at 490μm and 94°C provides the most consistent extraction of Don Joel Kenia's three top-ranked methods, because the flat-bottom geometry eliminates the center-channel bias that can affect SL28's large, slow-extracting beans in a cone dripper. SL28 produces a bimodal distribution when ground — the large beans generate fewer fines than smaller varieties, but the fines that do form extract very quickly while the large particles extract slowly. The Wave's flat bed distributes water pressure evenly across both particle sizes, reducing the extraction gap between fines and boulders. This directly improves the cup: when fine particles aren't over-extracting while large particles under-extract, the black currant and grapefruit notes appear clean rather than sour-bright-and-bitter simultaneously.
Troubleshooting
sour: Grind finer by ~22μm and raise temp to 95°C. SL28's large beans at 490μm in the Wave can produce sour cups if pulse pours are too aggressive and water runs through before extracting into the sweet phases. Slower pours plus tighter grind both increase contact time and pull the plum and brown sugar compounds through.
thin: Add 1g to dose or reduce water by 15g. Don Joel Kenia at 1:16-1:17 can run lean — washed light roast with no processing body contribution means TDS depends entirely on extraction. At the wide ratio end, the brown sugar note becomes imperceptible. More dose is the first adjustment.
AeroPress brews Don Joel Kenia at 85°C with a 360μm grind — 40μm finer than default to account for the light roast's reduced solubility. The finer grind ensures adequate extraction from SL28's dense cell structure in the short 1–2 minute brew window. The immersion-plus-pressure format naturally produces a more integrated cup than open pour-over methods, which can benefit SL28's intense brightness — the balance shifts slightly toward the plum depth and brown sugar sweetness rather than leading exclusively with the sharp grapefruit character. The sealed chamber preserves the aromatic complexity while pressure helps push extraction past what steeping alone would achieve. For drinkers who find SL28's brightness assertive in pour-over format, the AeroPress offers the same variety expression in a rounder, more integrated profile.
Troubleshooting
sour: Grind finer by ~22μm and raise to 86°C. AeroPress at 85°C and 360μm is balanced for SL28, but if steep time runs under 75 seconds, extraction stops before the plum and brown sugar phases. Extend steep to 90 seconds before pressing — the longer immersion compensates for the lower temperature.
thin: Add 1g to dose or reduce water by 15g. AeroPress at 1:12-1:13 already runs concentrated, but washed light SL28's high clarity means thin output signals incomplete extraction more than ratio mismatch. More mass or a metal filter to carry oils into the cup both work — metal filter also adds the body SL28 lacks at light roast.
The Clever Dripper at 490μm and 94°C gives Don Joel Kenia the immersion advantage that SL28's dense large beans benefit from: complete wetting before drainage begins ensures the grounds are evenly saturated before extraction rate drops off. For this variety, that matters because the slower-extracting compounds — the plum depth and the brown sugar sweetness — need full contact time without the flow interruptions that manual pour technique can introduce. The paper filter maintains the acid clarity that makes SL28 distinctive. At 1:15-1:16, the Clever produces a cup that's structurally close to a well-executed V60 but with less technique variability — making it the best daily-driver option for extracting SL28's full acid profile consistently.
Troubleshooting
sour: Grind finer by ~22μm and raise temp to 95°C. The Clever's immersion phase is SL28's friend, but if steep runs under 3 minutes, the large dense beans haven't fully extracted into the plum and brown sugar phases. Let it steep the full 3-4 minutes before releasing the valve. Finer grind also helps with insufficient contact.
thin: Add 1g to dose or reduce water by 15g. Washed light SL28 in the Clever produces clean output but depends entirely on TDS for body — no oils, minimal fines. If sweetness seems absent, TDS is below threshold. Increase dose first; the paper filter's clarity is worth preserving.
SL28 espresso is a specific experience. Under 9 bars of pressure, the sparkling acidity that gives SL28 its characteristic blackcurrant brightness amplifies into something intense and polarizing — vivid, almost electric fruit pressure in the cup. Light-roast espresso protocol applies: grind at 210μm, 93°C, preinfusion essential. SL28's large dense beans need more time to wet before full pressure builds; channeling through a dry puck produces sour, thin shots where only fast-extracting acids extract. The 1:1.9-2.9 ratio window at 19g dose means dialing toward 1:2.5 is recommended to build yield while maintaining TDS. This is not a mellow espresso — the grapefruit and blackcurrant will be vivid. That's what SL28 does under pressure.
Troubleshooting
sour: Grind finer by ~10μm and raise to 94°C. SL28 light roast espresso is the highest-acid shot in this batch — sour output is the primary failure mode. Long preinfusion (8-10s at 2 bar) before ramping is non-negotiable for this variety's large, dense beans. Pull toward 1:2.5 ratio to build extraction yield.
thin: Add 1g to dose or reduce yield by 5g (toward 1:2.2). SL28 light roast at the 1:2.9 ratio end loses TDS quickly — the dense beans can't extract fast enough at the extraction rate. Shorter ratio compensates. Preinfusion uniformity also directly increases TDS by eliminating dry channels through the puck.
Moka Pot at 310μm and 100°C pre-boiled water gives Don Joel Kenia a steam-pressure extraction that amplifies the SL28 character differently than espresso. At ~1.5 bar versus espresso's 9 bar, the acid concentration is less intense but the flavor compounds that require full extraction — the brown sugar sweetness and plum depth — have more time to dissolve without being driven by high pressure through a fine puck. The pre-boiled base water is essential: SL28 washed light is a high-density low-solubility bean, and cold water heating in the base would cook the grounds at the bottom of the basket before steam pressure builds, producing a sour-bitter hybrid. The 1:9-1:10 ratio produces a concentrated brew where the blackcurrant character reads as a rich fruit extract rather than the sharp acid-bright clarity of filtered methods.
Troubleshooting
sour: Grind finer by ~22μm and confirm pre-boiled water base. Sour Moka output with washed SL28 light roast means steam extracted only through the acid phase — the dense large beans need full basket saturation before pressure builds to extract into sweetness. Pre-boiling is the highest-leverage fix; finer grind is second.
thin: Add 1g to dose or reduce water slightly. Light roast SL28 in Moka Pot at 1:9-1:10 can produce thin, sour output if the seal isn't tight and pressure doesn't build fully. Confirm equipment seal first; then increase dose if concentration is the issue.
strong: Reduce dose by 1g or add a small amount to the base. Moka Pot with SL28 can concentrate the phosphoric and citric acids to an overpowering level — if the grapefruit and blackcurrant read as sharp and astringent rather than vibrant, TDS has overshot. Slightly less dose or more water in the base corrects this.
French Press is Don Joel Kenia's lowest-scoring filter method at 76/100, for a specific reason: SL28's intense acidity does not combine well with the oils and fines that metal-filtered extraction introduces. In a Chemex, the acid clarity is SL28's defining strength; in French Press, those same acids compete with tannins from unfiltered fines, producing a cup where blackcurrant and grapefruit tip toward harsh rather than vibrant. The recipe at 960μm and 96°C mitigates this somewhat — coarser grind reduces fine particle migration, and higher temperature helps extract fully within the steep window. Hoffmann's extended post-plunge settle is more important here than for most beans: letting grounds drop before pouring removes enough sediment to let SL28's acid character express more cleanly.
Troubleshooting
sour: Grind finer by ~22μm and raise temp to 97°C. French Press at 960μm with dense SL28 can produce sour cups if steep time runs short or grounds aren't fully submerged. Extend steep to 8 minutes and use Hoffmann's extra 5-minute post-plunge settle — cleaner decant reduces the phenolic compounds that make sourness harsh.
thin: Add 1g to dose or reduce water by 15g. SL28 in French Press loses some of its natural body potential because light roast produces fewer melanoidins. More coffee mass keeps TDS up — the metal filter also contributes cafestol and oils that add body if you don't mind slight turbidity in the cup.
Cold BrewFlash Brew Recommended
Cold brew is not recommended for this bean. At near-freezing temperatures, cold water cannot extract the complex acids, delicate aromatics, and bright fruit compounds that define a light-roasted coffee — they remain locked in the cell matrix. For a cold version of this coffee, use flash brew: brew a concentrated pour-over (V60 or Chemex at 60% of the normal water volume) directly over ice in the server. The hot water extracts the full flavor spectrum, and the rapid ice cooling locks in volatiles that would otherwise evaporate during a slow cool-down.